Facilitate the use of backup/restore for the business

[pith]

The backup/restore feature requires the implementation of an exporter and an importer. We should provide good defaults avoiding this overhead.

An idea could be to provide the following interface

public interface BackupableRepository<A extends Aggregate> {

    long count();

    // loadAll would not be a good idea for perf
    List<A> loadRange(Range range);

    void deleteAll();
}

Then by injecting the list of all the aggregate roots we could use the InternalRegistry to get all the BackupableRepository and iterate over them.

[pith]

Think to add Default implementation for this with qualifier based on the implementation.

By the way, this won't require the use of DTO as we don't want a representation of the domain, but the whole domain. Aggregates will be directly serialized in JSON or any format supported by the data-backup feature in Seed core.

[adrienlauer]

This is now supported with new repositories (#96) and the default importers/exporters (#97). It still requires a DTO because it is desired to avoid coupling the domain to any external representation.